Currently, perf allocates an array of page pointers which is limited in
size by MAX_PAGE_ORDER. That in turn limits the maximum Intel PT buffer
size to 2GiB. Should that limitation be lifted, the Intel PT driver can
support larger sizes, except for one calculation in
pt_topa_entry_for_page(), which is limited to 32-bits.

Fix pt_topa_entry_for_page() address calculation by adding a cast.

Fixes: 39152ee51b77 ("perf/x86/intel/pt: Get rid of reverse lookup table for ToPA")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 arch/x86/events/intel/pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 047a2cd5b3fe..b4aa8daa4773 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -990,7 +990,7 @@ pt_topa_entry_for_page(struct pt_buffer *buf, unsigned int pg)
 	 * order allocations, there shouldn't be many of these.
 	 */
 	list_for_each_entry(topa, &buf->tables, list) {
-		if (topa->offset + topa->size > pg << PAGE_SHIFT)
+		if (topa->offset + topa->size > (unsigned long)pg << PAGE_SHIFT)
 			goto found;
 	}
 
-- 
2.34.1

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     3520b251dcae2b4a27b95cd6f745c54fd658bda5
Gitweb:        https://git.kernel.org/tip/3520b251dcae2b4a27b95cd6f745c54fd658bda5
Author:        Adrian Hunter <adrian.hunter@intel.com>
AuthorDate:    Mon, 24 Jun 2024 23:10:57 +03:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 04 Jul 2024 16:00:21 +02:00

perf/x86/intel/pt: Fix pt_topa_entry_for_page() address calculation

Currently, perf allocates an array of page pointers which is limited in
size by MAX_PAGE_ORDER. That in turn limits the maximum Intel PT buffer
size to 2GiB. Should that limitation be lifted, the Intel PT driver can
support larger sizes, except for one calculation in
pt_topa_entry_for_page(), which is limited to 32-bits.

Fix pt_topa_entry_for_page() address calculation by adding a cast.

Fixes: 39152ee51b77 ("perf/x86/intel/pt: Get rid of reverse lookup table for ToPA")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240624201101.60186-4-adrian.hunter@intel.com
---
 arch/x86/events/intel/pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 047a2cd..b4aa8da 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -990,7 +990,7 @@ pt_topa_entry_for_page(struct pt_buffer *buf, unsigned int pg)
 	 * order allocations, there shouldn't be many of these.
 	 */
 	list_for_each_entry(topa, &buf->tables, list) {
-		if (topa->offset + topa->size > pg << PAGE_SHIFT)
+		if (topa->offset + topa->size > (unsigned long)pg << PAGE_SHIFT)
 			goto found;
 	}